Dry skin causes many skin disorders such as dry dermatitis. It requires a lot of time and medication to treat patients with skin disorder that cover a vast skin area. Although glycerin is a component of many skin care creams and cosmetics, there is no report regarding the effects of glycerin alone as a bathwater additive. We investigated the effects of bathing in warm water with added glycerin on skin conditions and the prevention of skin disorders in patients with severe motor and intellectual disabilities.
Two studies were conducted to analyze the effects of a glycerin+warm water bath (GWWB). In study 1, the skin conditions in a total of 18 subjects were compared between the glycerin group (G) and nonglycerin group (NG). In the G group, skin moisture, skin pH, and skin sebum were measured with a skin analyzer noninvasively at the forehead and precordial and lateral forearm after GWWB for approximately 6 months. Subjects in the 2 groups had bathed 2 times per week and were immersed in warm water at 40 to 41°C for 2 to 3min. In the G group, 250ml glycerin was added in a 14001 bathtub. In study 2, a total of 78 subjects were examined retrospectively; their medical records after GWWB for approximately 6 months were investigated to gain information regarding cutaneous diseases (number of diagnosis, drugs, areas affected with cutaneous diseases, and days of treatment) in order to compare the G and NG groups.
Skin moisture levels at forearm improved significantly (p<0.05) in the G group. The average skin moisture level in other areas was higher in the G group than in the NG group but without sig nificance. Skin sebum levels at the forehead improved significantly (p<0.05) in the G group. The number of diagnosis, drugs, and areas with cutaneous disease were significantly lower in the G group than in the NG group. Further, the average number of treatment days was lower in case of the G group than in case of the NG group but without significance.
The moisturizing effects are produced due to a thin film formed by glycerin after GWWB, especially in an area where there is friction between the skin and clothes. Skin sebum is also maintained due to glycerin-film formation.
It is possible that maintenance of skin moisture protects the skin from cutaneous diseases due to xerosis. In conclusion, these results indicate that GWWB maintains skin moisture and sebum and prevents skin disorders.

Objective: Warm water immeresion (WWI) has been customary in Japan as useful thermal therapy. However, a comprehensive investigation of the effects of WWI on internal organs has never been undertaken. The purpose of this study was to examine the effects of single WWI on indocyanine green (ICG) excretion in healthy humans. Subjects: 23 healthy males. (32.6±1.9 [mean±SEM] years) Methods: 1CG was administered intravenously (0.5mg/kg) to calculate excretion rate (ER). ICG injection was given before and after WWI (10min at 41°C). Sublingual temperature (ST), blood pressure (BP), heart rate (HR), and cardiac output (CO) were simultaneously measured by noninvasive methods. Results: Significant changes were observed after WWI. These included an increase in ST, HR, and CO and a decrease in systolic BP (p<0.01). ER significantly decreased from 0.210±0.015 to 0.168±0.009 (p<0.01). Front-back ratio of ICG-ER which was calculated in order to evaluate the effect of aging increased significantly with age (R=0.582, p<0.0001). Conclusion: These results indicate that although CO increased due to the vasodilating effects of WWI, hepatic blood flow decreased after WWI and its response reduced with age even in before middle age.

The effects of the bathing on renal function were studied in 12 healthy men (32.3±7.7y. o.). The subjects took 41°C, 10min bathing and kept warm by a blanket for 30min, and then a mixture of 10% para-aminohippurate (PAH, 0.3ml/kg) and 10% sodium thiosulfate (NTS, 80ml) was infused intravenously. Clearance of PAH and NTS was calculated as the index of renal plasma flow (RPF) and glomerular filtration rate (GFR). PAH and NTS clearance test was also done at rest without bathing in another day. Blood Pressure (BP), Heart rate (HR), cardiac output (CO), sublingual temperature by electric thermista as deep body temperature were measured during the experiment. 30min after bathing, sublingual temperature was significantly increased by 0.9°C, and CO by +40%. After bathing, renal plasma flow (PAH clearance) significantly increased from 388.5±158.9ml/min to 572±170.7ml/min. Glomerular filtration rate (NTS clearance) was, however, unchanged from 115.6±37.3ml/min to 119.3±51.3ml/min. Filtration fraction (GFR/RPF) was significantly decreased. These results indicated that GFR was not improved by bathing although CO and RPF was increased by thermal vasodilation effect. The mechanism of unchanged GFR, despite of increased RPF, is probably that glomerular filtration pressure unchanged by thermal vasodilation of glomerular efferent and afferent arterioles.

  Frequent bathtub bathing (BB) improves sleep quality and mental health of middle-aged and older Japanese individuals. This study investigated the chronic effects of BB with and without a bath additive (bathtub bathing with KIKIYU [BBK]) in healthy young adults. The study involved healthy young adults who habitually showered, as opposed to bathing. Nineteen participants were randomly assigned to either the BB or BBK groups for 14 consecutive nights. After a 2-week washout period (shower bathing), the participants were asked to switch their bathing styles (a crossover design). The artificial bath additive for the BBK group contained inorganic salts and carbon dioxide. The participants were evaluated by using the Oguri-Shirakawa-Azumi Sleep Inventory-Middle-aged version (OSA-MA) and 1-ch sleep electroencephalography (EEG) for sleep quality, the Profile of Mood States (POMS), Self-rating Depression Scale (SDS), and Apathy Scale (AS) for mental conditions.  Sleepiness on waking and refreshing scores in the OSA-MA significantly differed between the shower bathing and BBK groups. EEG results did not significantly differ among the bathing styles. Vigor T-score and total mood disturbance (TMD) scores showed significant differences in the two bathing groups (shower vs. bathing), and fatigue T-score was significantly lower in the BBK group compared with both the BB and shower groups. SDS score was significantly lower in the BBK group compared with the shower group. AS score was significantly lower in the two bathing groups (shower vs. bathing).   The OSA-MA score was possibly influenced by vasodilatation and circulation by using carbon dioxide and keeping the body warm after bathing by using inorganic salts. The OSA-MA score was possible also affected by fatigue alleviation and maintenance of vitality by using a citrus lemon scent and yellow-green hue. Furthermore, frequent body heating affects the central nervous function related to mood and emotion.  Based on these results, we can conclude that BB and BBK prior to shower bathing improved the mental health of the young adults in this study.

Objective: The purpose of this study was to examine the effects of bathtub bathing （BB） on sleep and working efficiency of healthy young adult students. Furthermore, the effects of BB and prolonged increased body temperature from the use of insulating sheets and sleeping bags after BB （warming after BB: BBW） on sleep and working efficiency were investigated. Subjects: Eighteen （six males, 12 females） healthy young students （19.6±0.7 years old, mean±SD） who habitually took showers instead of baths participated in this study. Informed consent was obtained from all of the subjects, and the study was approved by the Ethics Committee of Kumamoto Health Science University. Methods: Subjects were randomly assigned to two groups （n＝9 in each group）. The subjects in the BB group were immersed in their home bathtub to the supraclavicular level and instructed to rest for 10 min with the temperature regulated at 41°C. The subjects in the BBW group followed the same bathing protocol, and they then rested in a sleeping bag and sheet for 30 min in order to keep their bodies warm. The length of each study period was 2 weeks in a crossover design. After the 2-week-long washout periods, the subject groups were switched. The subjects were evaluated with the Oguri-Shirakawa-Azumi sleep inventory, MA version （OSA-MA）, which utilizes a visual analog scale （VAS） with which subjects rate their sleep when they wake up, and Purdue Pegboard Assembly test. These tests were employed before and after the BB and BBW sessions, resulting in four testing periods in the 6-week period. Results: Sleep rating on the OSA-MA was no significant difference in both the BB and BBW groups compared to ratings recorded after showering. The subjects in the BB and BBW groups had significantly increased VAS ratings for “Feeling of sound sleep,” “Refreshing,” and “Lightness of the body” compared to the ratings after showering. The mean Purdue Pegboard test scores of the subjects in both the BB and BBW groups were significantly higher than those recorded after showering. Discussion: Changing bathing style from shower to BB or BBW improved the working efficiency of students on the Purdue pegboard test. BB and BBW resulted in soothing effects owing to improvements in the subjects’ quality of sleep.

Introduction: Some students take showers instead of baths for economic reasons or because they dislike cleaning the bathtub. The purpose of this study was to examine the effect of bathing routines on students’ working efficiency. Subjects: Seventeen (six male and 11 female) healthy young students (19.6 ± 0.7 years old, mean ± SD) who habitually took showers instead of baths participated in this study. Informed consent was obtained from all the subjects and the study was approved by the Ethics Committee of Kumamoto Health Science University. Method: Subjects were randomly assigned into two groups. The subjects in the first group (bathtub bathing [BB]) were immersed to the supraclavicular level in their home bathtub and instructed to rest for 10 minutes with the temperature regulated at 41°C. The subjects of the second group (whole-body warming after BB [BBW]) followed the same bathing protocol and then rested in a sleeping bag and sheet for 30 minutes to keep their bodies warm. Each period was carried out over 2 weeks in a cross-over design. Washout periods were 2 weeks long. The evaluation items of this study included the obstructive sleep apnea (OSA) sleep inventory MA version (OSA-MA), a questionnaire containing a visual analog scale (VAS) to judge the subjective bathing effect, profile of mood states, salivary stress marker (α-amylase), and the Purdue Pegboard test. These tests were evaluated before and after the BB sessions, BBW sessions, and washout interval for a total of four times in a 6-week period. Result: Participants tended to report a better sleep feeling on the OSA-MA after the BB or BBW sessions than after showering. There were significantly better changes in both the BB and BBW in the VAS for bathing effect in terms of “Sense of deep sleep,” “Body fatigue,” “Light feeling of the body” than after a shower. The mean α-amylase value in the saliva of the BBW group participants was significantly lower than that after showering. The mean Purdue Pegboard test scores of both the BB and BBW sessions were significantly higher than that after the shower. Discussion: Sleep quality seemed to be more improved after BB or BBW than after showering, perhaps due to reduced stress. Work efficiency also increased in the BB and BBW groups.

Objective: The purpose of this study was to clarify the chronic effects of bathtub bathing (BB), whole body warming after bathtub bathing (BBW), and bathtub bathing with herbal extracts (BBH) on the mental condition of healthy young persons. Subjects and Methods: Experiment 1: Eighteen (6 male and 12 female; age: 19.6±0.7 years, mean ± SD) healthy young persons who were taking a shower habitually but not bathtub bathing participated in this study.   From November 2012 to December 2012, subjects were randomly assigned into two groups (each 3 male, 6 female): those who had BB or 30-min BBW 14 times for 14 consecutive nights during a 2-week period. After a 2-week washout period, subjects were asked to switch their bathing conditions (a cross-over design). Experiment 2: Twenty (8 male and 12 female; age: 21.3±1.6 years, mean ± SD) healthy young persons who were taking a shower habitually but not bathtub bathing participated in this study.   From October 2013 to November 2013, subejects (4male and 6 female) were randomly assigned to undergo BB or BBH.   The herbal extract contained Dong dang gui (Japanese Angelica Root), Chimpi (Citrus Unshiu peel), Chamomilla recutita, and ginger extracts.   After a 2-week washout period, subjects were asked switch to the other bathing condition (a cross-over design).   All participants provided informed consent for participation in these studies, and these studies were approved by the Ethics Committee of the Kumamoto Health Science University.   The subjects immersed their bodies up to the supraclavian for 10 min, in tap water adjusted to a temperature of 41 °C in their bathtub at home. The subjects’ mental conditions were assessed using Profile of Mood States short version questionnaire.   The differences in the effect of BB and BBW, as well as those of BB and BBH on the subjects’ mental conditions and their mental conditions pre-BB and post-BB, pre-BBW and post-BBW, pre-BBH and post-BBH were analyzed using Wilcoxon’s signed-rank sum test. Results: The points for depression-dejection, fatigue, and confusion in those who had BBH significantly converged to the median average (50 points) compared to the points in those who had BB.   The points for anger-hostility before BBW and BBH significantly converged to the median average (50 points) after BBW and BBH, and there were no significant differences in points before and after BB. Conclusions: The subjects’ anger-hostility was influenced by body warming in BBW and the vasodilatory components of the herbal extracts.   The subjects’ depression-dejection and fatigue was influenced by the fragrance and color of herbal extracts.